From dac2a4f663c4bcd75add07aedf9d30c9f8e5ead5 Mon Sep 17 00:00:00 2001 From: Frank van der Linden Date: Thu, 1 May 2025 04:43:24 +0000 Subject: [PATCH] mm/hugetlb: copy the CMA flag when demoting Since commit d2d786714080 ("mm/hugetlb: enable bootmem allocation from CMA areas"), a flag is used to mark hugetlb folios as allocated from CMA. This flag is also used to decide if it should be freed to CMA. However, the flag isn't copied to the smaller folios when a hugetlb folio is broken up for demotion, which would cause it to be freed incorrectly. Fix this by copying the flag to the smaller order hugetlb pages created from the original one. Link: https://lkml.kernel.org/r/20250501044325.20365-1-fvdl@google.com Fixes: d2d786714080 ("mm/hugetlb: enable bootmem allocation from CMA areas") Signed-off-by: Frank van der Linden Reviewed-by: Anshuman Khandual Reviewed-by: Oscar Salvador Reviewed-by: Jane Chu Cc: Muchun Song Signed-off-by: Andrew Morton --- mm/hugetlb.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index e3e6ac991b9c..6ea1be71aa42 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4034,10 +4034,13 @@ static long demote_free_hugetlb_folios(struct hstate *src, struct hstate *dst, list_for_each_entry_safe(folio, next, src_list, lru) { int i; + bool cma; if (folio_test_hugetlb_vmemmap_optimized(folio)) continue; + cma = folio_test_hugetlb_cma(folio); + list_del(&folio->lru); split_page_owner(&folio->page, huge_page_order(src), huge_page_order(dst)); @@ -4053,6 +4056,9 @@ static long demote_free_hugetlb_folios(struct hstate *src, struct hstate *dst, new_folio->mapping = NULL; init_new_hugetlb_folio(dst, new_folio); + /* Copy the CMA flag so that it is freed correctly */ + if (cma) + folio_set_hugetlb_cma(new_folio); list_add(&new_folio->lru, &dst_list); } }